Bosnian pine (Pinus heldreichii Christ) - PIHE, is a species native to mountainous areas of the Balkans and southern Italy. PIHE is a tree species of the upper tree line in the Dinaric mountains and as such a promising source of valuable climate information. Due to its longevity it might have a good potential for long climate reconstructions based solely on living trees. The aim of our study was to investigate potential of PIHE: (1) for construction of long PIHE chronologies for the region of the central W Balkan, and (2) for long climate reconstructions based mostly on cores from living trees. Preliminary PIHE chronology is 437-years (1573-2009) long and has a sufficient sample depth for EPS)0.85 from 1659 onwards. Comparison with climate data show specific response of PIHE to climate – trees respond positively to above average temperature in March (Mt) and negatively to above average temperature in June and July (JJt). We found weak positive response to June and July precipitation (JJp). This is somehow expected since precipitation is abundant along the Dinaric mountain ridge and are not factor in minima. Running window statistics reveal a significant temporal change in the identified signals – JJt and JJp signals were significant before 1965 and Mt after 1965; both temperature and precipitation loose signal after 1965. Although already quite long, PIHE chronology can be extended by adding additional old trees from the studied region. Climate signal in tree-rings is somehow specific compared to other trees species in the region (e.g. Pinus nigra). JJt and JJp seems to play an important role in the formation of tree-rings (see also Seim et al. 2012), however a clear positive March temperature signal in PIHE tree-rings after 1965 and almost complete disappearance of the JJt and JJp signal after 1965 deserves attention as well. The reasons for that are yet to be investigated.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 3860902Differences between differently vital groups of pedunculate oaks (Quercus robur) were determined in diameter increment and wood-anatomical features. Ring-width and latewood chronologies were standardized using modified negative exponential curve. Large-scale drainage manipulation in 1982 in forest stand from Cigonca first caused changes in ring width, latewood and parameter "total vessel area". Not until the year 1995 signs of dieback are also visible in smaller sizes of conductive elements. "Strongly Declining" group from Cigonca is responsive only to the mean monthly and seasonal temperatures. Dependence is strictly negative - for dendrochronological and wood-anatomical parameters. "Vital" and "Declining" groups from Mlače are responsive to the mean temperatures and the sum of precipitations. Wood-anatomical parameters from "Vital" group from Mlače showed higher responsive rate to temperatures than dendrochronological parameters, which are mostly responding to June precipitation. Higher winter and spring precipitation cause smaller conductive elements but do not affect the "total vessel area". Parameter "maximal vessel area" was recognized as a potential parameter for reconstruction of mean temperatures from March to June.
D.10 Educational activities
COBISS.SI-ID: 3816614An unknown event in 1929 caused radial growth decline of Pinus nigra Arn. (PN) trees on one of the sampled site in Bosnia and Herzegovina (Poljanšek et al., 2012). Needle trace method (NTM), which retrospectively examines the needle shedding through the life-time of the studied trees (Kurkela and Jalkanen, 1990), revealed sudden loss of all needle age classes on PN trees in the growing season of 1929 (Poljanšek et al., 2013). In the affected stand, PN grows together with P. sylvestris L. (PS) trees. To determine if PS trees, too, were affected in the 1929 event, our research was extended to PS trees. The sampled PS trees were up to 180 years old and 18m high. On average, there were 3.5 needle sets on the main stem, while average age of needles at the time of their shed was 2.9 years. Radial and height growth decline in all PS trees was similar to growth decline of PN trees in 1929, but needle shed pattern is not that clear. Data on needle shed in 1929 is not complete due to the damage in main stems. Nonetheless, results confirmed needle loss of all age classes in all trees but the tallest PS tree. Needle shed of the other PS trees is consistent with results of PN trees. NTM evidenced the abrupt needle shed on two pine species in one growing season, which resulted in growth decline. Possible reasons for such a massive loss of needles could be defoliation by fungi, insects or destruction of crown by wildfire. With consideration that needles of all age classes were affected in two different pine species and on trees of various heights, wildfire and/or extreme heat spell/drought-related-events should also be addressed as the main reason for needle shed and consequential growth decline.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 3860646